This invention relates to release backing layers which may be formed on polymer-backed floor covering to allow carpet or carpet padding to be easily removed from its underlying surface, yet which resists buckling or folding when such carpet is rolled.
Manufacturing methods have been devised and improved for producing, polymer-backed floor covering, particularly polyurethane foam-backed carpets.
One previously unsolved problem in connection with polymer-backed floor covering and particularly in connection with polyurethane foam-backed carpet however, relates to installation. When it was necessary to remove a glued down polymer backed carpet, the installer was faced with significant cost and effort. Typically, where multipurpose adhesives were used, the bond between the bottom of the polymer backing and the underlying surface would be sufficiently strong to cause the carpet to delaminate or the polymer backing to separate as the carpet was being pulled up, and thus to leave a residue of adhesive and portions of the polymer backing on the floor. This residue would have to be mechanically removed by scraping or vibrating, resulting in significant additional cost. Often, these costs exceed the entire cost of replacing and installing the new carpet.
Such removal problems were to some extent alleviated with the advent of pressure sensitive adhesives, which in theory never fully harden, so that carpet may be applied, removed and reapplied repeatedly. However, due to the lack of internal strength in most polyurethane foam carpet cushions, portions of the polyurethane foam cushion would remain bonded to the floor even when these pressure releasable adhesives were used. Time-consuming, expensive removal was therefrom required.
The significance of this problem is demonstrated by the prevalence of an alternative method of securing carpeting by the use of tack strips. In the tack strip method, wooden strips are secured to the floor or underlying surface around the perimeter of the room. Padding is then placed on the surface and carpet is stretched over the padding and tacked to the strips. Removal of tacked down carpet leaves no residual adhesive or polymer backings. The tack strip method, however, requires skilled and trained installers and is expensive.
These preexisting installation methods illustrate the desirability of a polymer-backed carpet which can be glued to the floor using a pressure sensitive adhesive and removed some time later by simply pulling the carpet from the floor, leaving the adhesive layer in a tacky state ready for installation of the next carpet. Such a method allows installers to change home carpeting using minimum time and effort. In the contract carpet market, removal and installation costs are significantly lower.
One proposed solution to the foregoing problem is to bond a release backing layer to the underside of such carpet. The release backing layer may then be glued to the floor. When such a carpet is pulled from the floor, the release backing layer provides the carpet with sufficient mechanical strength to remain substantially intact.
However, the addition of such a release backing to a carpet has been found to cause additional stiffness. One may particularly notice the effects of such stiffness when a polymer-backed carpet having a stiff secondary backing layer is rolled for storage. Heretofore, when such carpet was rolled toward the secondary backing, the secondary backing was unable to absorb the compressive forces placed on it by being rolled inside of the primary backing layer, and therefore buckled or folded. Such buckling and folding caused indentations in the polymer backing and facing layers of the carpeting, which remain visible in the carpet long after it is installed.